Generation of a recombinant Fab antibody reactive with the Alzheimer's disease-related Abeta peptide

A recombinant Fab antibody, designated 1E8-4b, which reacts with the Alzheimer's disease (AD)-related Abeta peptides, Abeta[1-40], Abeta[1-42] and Abeta[1-43] has been developed. The 1E8-4b Fab was constructed by cloning the V(H)C(H1) and V(L)C(L) domains from the parent hybridoma 1E8 antibody, reported previously to recognize these Abeta peptides. Briefly, a C-terminal Flag tag sequence was incorporated into this construct, which was ligated into the vector pHFA2 and expressed in Escherichia coli. Following purification on an M2 anti-Flag affinity column, the 1E8-4b recombinant Fab antibody was shown to bind plaques within sections of brain tissue from CERAD-defined AD patients by immunohistochemistry. ELISA, epitope mapping and immunoblotting confirmed the recognition of the Abeta1-40/42/43] peptides by the 1E8-4b Fab. The 1E8-4b Fab did not recognize APP695 or APP770 which contain the Abeta sequence. The Abeta specificity of the recombinant 1E8-4b Fab antibody was identical to the parent 1E8 monoclonal antibody.

Identification of structural variations in the carboxyl terminus of Alzheimer's disease-associated beta A4[1-42] amyloid using a monoclonal antibody

The accumulation of amyloid plaques and amyloid congophilic angiopathy (ACA) in the brains of affected individuals is one of the main pathological features of Alzheimer's disease. Within these deposits, the beta A4 (Ass) polypeptide represents a major component with the C-terminal 39-43 amino acid variants being most abundant. Using a mouse IgG1 MoAb produced by hybridoma beta A4[35-43]-95.2 3B9, which reacts with the epitope is defined by the amino acid residues beta A438[GVV]40, this study has identified a unique conformation within the carboxyl terminus of human beta A4[1-42]. Although the beta A438[GVV]40 sequence is present within the C-termini of human beta A4[1-40] and beta A4[1-43] and the beta A4-containing region of human APP, the beta A4[35-43]-95.2 3B9 MoAb (designated MoAb 3B9) does not bind these polypeptides, demonstrating a high degree of specificity for the beta A438[GVV]40 epitope as presented within the beta A4[1-42] sequence. The beta A4[1-42] epitope bound by MoAb 3B9 is sensitive to heating (100 degrees C for 5 min) and is denatured by SDS but not by oxidative radio-iodination of beta A4 or by adsorption to plastic surfaces or nitrocellulose. The recognition of beta A4 plaque deposits and ACA by MoAb 3B9 within formalin-fixed sections of human AD brain demonstrates the potential of these antibodies for investigating the role of the unique beta A4[1-42] conformation in the development of Alzheimer's disease.

Vertebrate phylogeny of antigen D10: identification of a conserved foregut cell lineage

The monoclonal antibody 5HL-5D11-D10 to antigen D10 identifies a cell lineage that is restricted to certain tissues of the human foregut. We investigated the tissue distribution of antigen D10 in mammals, birds, reptiles, amphibians and fish by immunohistochemical staining. Tissue from human and each of ten other mammalian species showed staining of gastric mucous neck cells and glands of the cardia and antrum, Brunner's glands, peribiliary glands and periductal glands of the pancreas. Six of the mammalian species also expressed antigen D10 in mucosa of the larger bronchi, and five expressed it to varying degree in small bowel distal to the duodenum and in colon (three of these five species). Antigen was not detected in any of the three species of bird studied. Both reptiles and amphibians showed strong staining for antigen D10 in the gastric mucous neck cells and pyloric glands, and in a subpopulation of secretory cells in the oesophagus, with the amphibian also expressing antigen in some epithelial cells of the mouth and lung. Although absent from two species of bony fish, antigen D10 was expressed by small groups of epithelial cells of the intestine of a shark, and generally by the epithelial and connective tissue cells of the gut and gills, and hepatocytes of one species of ray. The presence of antigen D10 in different tissues and species was confirmed by both an indirect ELISA and immunoblot analysis of tissue extracts. Our observations suggest that the D10 epitope characterises a subpopulation of mucus-secreting cells, predominantly of the foregut and associated organs, which has been conserved throughout terrestrial vertebrate evolution.

Processing of the Alzheimer's disease amyloid precursor protein in Pichia pastoris: immunodetection of alpha-, beta-, and gamma-secretase products

betaA4 (Abeta) amyloid peptide, a major component of Alzheimer's disease (AD) plaques, is a proteolytic product of the amyloid precursor protein (APP). Endoproteases, termed beta- and gamma-secretase, release respectively the N- and C-termini of the peptide. APP default secretion involves cleavage within the betaA4 domain by alpha-secretase. To study the conservation of APP processing in lower eukaryotes, the yeast Pichia pastoris was transfected with human APP695 cDNA. In addition to the full-length integral transmembrane protein found in the cell lysate, soluble/secreted APP (sAPP) was detected in the culture medium. Most sAPP comprised the N-terminal moiety of betaA4 and corresponds to sAPPalpha, the product of alpha-secretase. The culture medium also contained minor secreted forms detected by a monoclonal antibody specific for sAPPbeta (the ectodomain released by beta-secretase cleavage). Analysis of the cell lysates with specific antibodies also detected membrane-associated C-terminal fragments corresponding to the products of alpha and beta cleavages. Moreover, immunoprecipitation of the culture medium with three antibodies directed at distinct epitopes of the betaA4 domain yielded a 4 kDa product with the same electrophoretic mobility as betaA4 synthetic peptide. These results suggest that the alpha-, beta-, and gamma-secretase cleavages are conserved in yeast and that P. pastoris may offer an alternative to mammalian cells to identify the proteases involved in the generation of AD betaA4 amyloid.

Subcellular localization of the Alzheimer's disease amyloid precursor protein and derived polypeptides expressed in a recombinant yeast system

Different isoforms and derived polypeptides of the Alzheimer's disease amyloid protein precursor (A beta PP) have been expressed in the yeast Pichia pastoris. The expression characteristics of the different A beta PP polypeptides were studied by post-embedding immunogold electron microscopy with various A beta PP antibodies. The site of intracellular expression could be readily identified with specific antibodies. Full length A beta PP was expressed in association with the nuclear membrane and the endoplasmic reticulum. Secretory derivatives of A beta PP were localized in membrane-bound secretory vesicles. A construct encoding two copies of beta A4[1-42] linked head-to-tail (beta A4duplex) accumulated as irregular dense cytoplasmic and intranuclear inclusions which reacted with all beta A4 antibodies tested. A beta A4-C-terminal construct accumulated into membranous structures in the cytoplasm and nucleus and reacted with most antibodies to beta A4 and the cytoplasmic domain of A beta PP. The two shorter constructs containing the beta A4 sequence formed similar intranuclear aggregates to those reported for intranuclear inclusions of polyglutamine peptides from huntingtin (in Huntington's disease) and ataxin protein fragments (in spinocerebellar ataxia). This is of interest because intracellular aggregation of the polyglutamine and beta A4 peptides may affect cells by similar toxic mechanisms. These studies demonstrate clear differences in the expression properties of different A beta PP polypeptides.

Alzheimer's disease-associated presenilin 1 in neuronal cells: evidence for localization to the endoplasmic reticulum-Golgi intermediate compartment

The recently identified Alzheimer's disease-associated presenilin 1 and 2 (PS1 and PS2) genes encode two homologous multi membrane-spanning proteins. Rabbit antibodies to the N-terminal domain of PS1 detected PS1 in human neuroblastoma SH-SY5Y wild type and PS1 transfectants (SY5Y-PS1) as well as in mouse P19, in CHO-K1 and CHO-APP770 transfected cells, in rat cerebellar granule and hippocampal neurons, and astrocytes. Immunoblotting detected full-length protein of 50 kDa, and a major presumptive cleavage product of 30 kDa. The immunofluorescence pattern resembled labeling of the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) marker protein ERGIC-53. PS1 distribution showed slight condensation after brefeldin A and more marked condensation after incubation of cells at 16 degrees C, characteristic of the ERGIC compartment. Double labeling showed colocalization of ERGIC-53 with PS1 in the SY5Y-PS1 cells. PS1 labeling of SY5Y-PS1 and P19 cells showed overlap of the cis-Golgi marker p210 and colocalization with p210 after brefeldin A which causes redistribution of p210 to the ERGIC. Expression of PS1 did not change in level or cellular distribution during development of neurons in culture. Double labeling for the amyloid precursor protein (APP) and PS1 on SY5Y-PS1 cells and CHO-APP770 cells showed some overlap under control conditions. These results indicate that PS1 is a resident protein of the ERGIC and could be involved in trafficking of proteins, including APP, between the ER and Golgi compartments.

Effect of intraperitoneally, intravenously and intralesionally administered monoclonal anti-beta-FGF antibodies on rat chondrosarcoma tumor vascularization and growth

The growth and vascularization of many tumours has been reported to be associated with the overexpression of the potent mitogenic and angiogenic polypeptide basic fibroblast growth factor (beta-FGF). Consequently, it has been proposed that inhibition of beta-FGF action would prevent the growth of beta-FGF-dependent tumours. In this study, cell culture assays were established to assess the ability of mouse monoclonal DG-2 anti-beta-FGF antibodies to inhibit the mitogenic action of beta-FGF in vitro. Following in vitro characterisation, the monoclonal DG-2 antibodies were used to evaluate the role of beta-FGF in promoting the vascularization and growth of rat chondrosarcoma tumours. The effect the monoclonal anti-B-FGF antibodies had on tumour vascularization and growth in vivo were monitored using a 99m Technetium (99mTc)-labelled red blood cell procedure. The characterization studies confirmed that the DG-2 monoclonal antibody recognised beta-FGF and inhibited its mitogenic action on mouse Balb/c cells and bovine endothelial cells in vitro. When examined in vivo, intralesional administration of mouse monoclonal DG-2 antibody significantly inhibited rat chondrosarcoma growth and vascularization. However when the monoclonal DG-2 antibody was administered intraperitoneally or intravenously no attenuation of rat chondrosarcoma tumour vascularization or growth was observed. This report has confirmed the potential effectiveness of anti-beta-FGF antibodies in the regulation of tumour growth. It has also demonstrated that further studies on the pharmacokinetics of administered antibodies and their mode of delivery are required so that the effectiveness of such anti-growth factor immunotherapy can be assured.

Detection of two isotypically different antibodies produced by a murine hybridoma

A hybridoma, F31P46B, secreting monoclonal antibodies (mAbs) comprised of mu and gamma heavy chains in association with a single kappa light chain, has been characterized. This hybridoma was prepared by fusing splenocytes, derived from a BALB/c mouse immunized with Vibrio vulnificus and SP2/O-Ag-14 mouse myeloma cells. The specificity of this hybridoma was determined by ELISA screening on a large number of bacterial strains. Hybridoma cells of F31P46B were cloned by limiting dilution to an average cell density of 0.1 cells/well and repeated 3 times to ensure monoclonality. Isotyping of 7 subclones was then performed by Ouchterlony gel double diffusion, as well as a Bio-Rad isotyping kit, and both methods showed that both IgM and IgG2b were secreted. PAGE and immunoblotting showed the presence of mu, gamma, and kappa chains with respective molecular weights of 80, 50, and 25kDa. A series of fractions, collected from F31P46B ascites during Superose 12 gel chromatography, were tested by the two isotyping methods and each confirmed the presence of two immunoglobulin products. These data indicated that the hybridoma secreted two separate immunoglobulins, IgM/kappa and IgG2b/kappa.

Rabbit polymorphonuclear neutrophils form 35S-labeled S-sulfo-calgranulin C when incubated with inorganic [35S]sulfate

Rabbit peritoneal polymorphonuclear neutrophils reduced inorganic [35S]sulfate to [35S]sulfite in vitro, concomitant with incorporation of 35S into a 10.68-kDa cytosolic protein as a S-[35S]sulfo-derivative. Amino-terminal sequencing of the purified protein identified calgranulin C, a member of the S100 protein family. cDNA clones of calgranulins B and C were isolated using oligonucleotide primers based on the established amino acid sequences of other mammalian calgranulins. The complete amino acid sequence of rabbit calgranulin C was deduced from the nucleotide sequence of the corresponding cDNA. It comprises 91 amino acid residues, has a calculated molecular mass of 10.52 kDa, has 74% identity with porcine calgranulin C, and shows high homology with other S100 calcium-binding proteins. Rabbit calgranulin C has a single cysteine residue at position 30, which we believe to be modified to S-[35S]sulfo-cysteine as a consequence of sulfate reduction by neutrophils. The formation of S-[35S]sulfo-calgranulin C appears to be a reaction specific to neutrophils. The specific radioactivity of calgranulin C from the neutrophil culture medium was 50-fold greater than that of the calgranulin C within the cells, suggesting that S-sulfation of calgranulin C might be associated with its secretion.

Monoclonal anti-H1 histone autoantibodies from unimmunized Balb/c mice. Specificity and VH and VL domain sequences

Examination of the nuclear reactivities of monoclonal IgM kappa autoantibodies, secreted by GFM-5 1B12 and NU-6 1F12 hybridomas derived from germ-free and nude mice, respectively, demonstrated homogeneous nuclear immunofluorescence staining patterns consistent with the recognition of histones. Under these conditions, GFM-5 1B12 and NU-6 1F12 mAbs produced species non-specific binding to components within the nuclei of mouse, human and Drosophila melanogaster cells. Immunoblotting confirmed the binding of these two autoantibodies to autologous H1 histones as well as bovine and insect H1 histones. Identification of the epitopes bound by GFM-5 1B12 and NU-6 1F12 mAbs within the D. melanogaster H1 histones was undertaken using 248 overlapping octapeptides encompassing the entire sequence of D. melanogaster H1 histones. GFM-5 1B12 mAbs bound several octapeptides derived from the amino- and carboxyl-terminal regions of D. melanogaster H1 histones with accessible KT, AT or VT amino acids. NU-6 1F12 mAbs, which stained nuclei within sections of D. melanogaster lavae, failed to bind to any of the 248 linear octapeptides, implying recognition of a conformational H1 histone epitope by this autoantibody. ELISA analysis of the polyspecific binding properties of GFM-5 1B12 and NU-6 1F12 mAbs demonstrated that both antibodies exhibited unique polyspecificity profiles. GFM-5 1B12 mAbs recognized bovine carbonic anhydrase and mouse IgG1, while NU-6 1F12 bound bovine cardiolipin, rat cytochrome c, Escherichia coli beta-galactosidase, toxoid from Clostridium tetani, mouse IgG1 and the haptens, DNP and FITC from the 24 antigen test panel. Comparison of the VH and VL domain sequences of GFM-5 1B12 and NU-6 1F12 mAbs demonstrated that the variations in autoreactivity and polyspecificity profiles resulted from amino acid variations in the CDRs of the VH and VL domains of these autoantibodies. Significantly, major differences in the VH domain sequences of the NU-5 1F12 and GFM-5 1B12 mAbs suggest that the VH domains may preferentially contribute to the unique specificities of the two anti-H1 histone autoantibodies.

In vitro inhibition of the actions of basic FGF by a novel 16 amino acid peptide

A composite procedure involving molecular modelling and a property-pattern algorithm, the Resonant Recognition Model (RRM), has been applied to structure-function studies with basic fibroblast growth factor (bFGF). Property-pattern characteristics for biological activity and receptor recognition for a group of FGF-related proteins were defined and then used to aid the design of a set of peptides which can act as bFGF antagonists. Molecular modelling techniques were then employed to identify the peptide within this set with the greatest conformational similarity to the putative receptor domain of bFGF. This 16 amino acid residue peptide (16mer), which exhibits no sequence homology to bFGF, antagonised the stimulatory effect of bFGF on fibroblast [3H]thymidine incorporation and cell proliferation, but exerted no effect itself in these in vitro bioassays.

Characterization of the specificity of a naturally-occurring monoclonal anti-thymocyte autoantibody derived from an unimmunized, neonatal Balb/c mouse

The immune repertoire of healthy unimmunized Balb/c mice contains a significant proportion of B lymphocytes which produce natural autoantibodies. The majority of these predominantly CD5+ B lymphocytes, secrete autoantibodies which react with conserved intracellular autoantigens such as actin, myosin and DNA. Significantly fewer autoreactive B lymphocytes produce natural autoantibodies reactive with cell surface autoantigens. In the present study, the specificity of monoclonal IgM kappa anti-thymocyte autoantibodies from hybridoma NMT-1 (NMT-1 maAbs), derived from the spleen of an unimmunized 8-day-old inbred Balb/c mouse has been examined. Anti-thymocyte NMT-1 maAbs reacted with cell surface molecules on 86-87% thymocytes from mice 1-28 days of age. Thymus-restricted expression of the identified autoantigen was demonstrated by the lack of detectable reactivity of NMT-1 maAbs to cell surface molecules of Balb/c mouse splenocytes, PBLs, lymph node, peritoneal and bone marrow cells and tissues including brain, liver and kidney. Furthermore, multiparameter flow cytometry demonstrated an association between the expression of the cell surface autoantigen identified by NMT-1 maAbs and thymocyte maturation as 94-97% of the CD4+ CD8+ thymocytes expressed the identified autoantigen which was largely absent from CD3+ thymocytes and not expressed in the peripheral immune system. Tissue distribution, flow cytometry and competition analysis indicated differences between identified T lymphocyte markers, including Thy-1, and the autoantigen identified by NMT-1 maAbs in this study. Immunoprecipitation analysis, however, revealed that NMT-1 maAbs reacted with 14.5 and 18.3 kDa Thy-1-related autoantigens within Balb/c mouse thymocyte membrane extracts, possibly unique glycosylated forms of the Thy-1 molecule.

Effects of trait anxiety and the scamper technique on creative thinking of intellectually gifted students

This work assessed the effect of trait anxiety (measured on the State-Trait Anxiety Inventory) and the Scamper technique on figural creative thinking, measured by the Torrance Tests of Creative Thinking. An analysis of covariance with 52 gifted students in a summer camp gave no significant main effect of treatment for trait anxiety, or their interaction. Scamper may not effectively improve figural creativity and anxiety may not influence figural creativity the same way it influences verbal creativity, at least as measured.

Identification of components of the endoplasmic reticulum and Golgi complex by murine autoreactive monoclonal antibodies

A number of autoreactive monoclonal antibodies have been produced by the fusion of spleen cells from unprimed BALB/c mice. The specificities of two of these monoclonal autoantibodies, MUI 38 and MUI 100, have been further examined. By indirect immunofluorescence, monoclonal antibody MUI 38 showed discrete perinuclear staining of acetone-fixed murine 3T3 fibroblasts, which was similar to that obtained with the Golgi vital stain, C6-NBD-ceramide, and with rhodamine-labelled wheat germ agglutinin. Furthermore, the staining pattern with antibody MUI 38 in cells treated with either monensin, taxol or nocodazol was altered in a manner consistent with the known effects of these drugs on Golgi morphology. In contrast, monoclonal antibody MUI 100 showed a diffuse cytoplasmic staining pattern, similar to FITC-Con A, indicative of reactivity with the endoplasmic reticulum. At high dilutions antibody MUI 100 showed only a perinuclear staining pattern, indicating that MUI 100 reacted with the Golgi as well as the endoplasmic reticulum. Both monoclonal antibodies are IgM kappa class and both showed reactivity with acetone-fixed fibroblasts from a number of species, indicating that the antigens are highly conserved. By immunoblotting with total membranes of murine 3T3 cells under either reducing or non-reducing conditions, monoclonal antibody MUI 100 reacted with a number of components with apparent molecular weights (MW) from 27,000 to 63,000. This reactivity was abolished when the 3T3 membranes were treated with sodium periodate, indicating antibody MUI 100 may be specific for carbohydrate. In addition, MUI 100, but not MUI 38, possessed rheumatoid factor activity, reacting with IgG from normal sera of a number of different species. Furthermore, monoclonal antibody MUI 100 was shown to be specific for the Fc domain of IgG. Absorption of MUI 100 antibody with normal rabbit IgG-Sepharose reduced the anti-endoplasmic reticulum reactivity, therefore both activities are attributable to the same antibody.

Effects of the Scamper technique on anxiety and creative thinking of intellectually gifted students

This study assessed the effect of the Scamper technique on creative thinking and trait-anxiety of 27 junior high students. Effect size was large for flexibility and medium for trait anxiety which suggests Scamper may be useful to improve flexibility and reduce trait-anxiety.

Autoantibodies to intermediate filaments in acute viral hepatitis A, B and non-A, non-B are directed against vimentin

Using ELISA and immunoblotting, autoantibodies to vimentin were sought in sera from 10 patients with acute hepatitis A, 10 with acute hepatitis B, 13 with acute non-A, non-B hepatitis, 16 with autoimmune chronic active hepatitis, 17 with cytomegalovirus infection and 40 from healthy persons. The ELISA results were expressed as a percentage of the value obtained with a monoclonal antibody to vimentin. The results (mean and SD) for acute hepatitis A (51.2 +/- 21.7%), acute hepatitis B (44.5 +/- 28.2%) and acute hepatitis non-A, non-B (43.0 +/- 16.4%) were significantly (p less than 0.01) higher than those for autoimmune chronic active hepatitis (20.5 +/- 7.7%), cytomegalovirus infection (25.9 +/- 12.2%) and healthy controls (16.8 +/- 9.3%). Immunoblotting showed that sera from patients with acute viral hepatitis reacted with 57 kd vimentin in triton-cytoskeletal extracts of fibroblasts. These results show that autoantibodies to vimentin are present in sera from patients with acute hepatitis A, B and non-A, non-B. Antivimentin autoantibodies may be useful in the diagnosis of acute non-A, non-B hepatitis.

Monoclonal antibody to myosin derived from mice immunized with gastric mucosal cells

A monoclonal IgMk antibody secreted by a hybrid (MUI-6) of mouse plasmacytoma NS-1 with spleen cells from a mouse immunized with canine parietal cell-enriched gastric mucosal cells was tested for immunofluorescence reactivity with gastric mucosal cells, tissue sections and monolayer cultures of rat fibroblasts. The antibody did not react with the cell membrane of parietal cells but reacted with smooth muscle fibres and skeletal muscle striations. In non-muscle cells, the antibody reacted with parietal cell cytoplasm, liver in a "polygonal" pattern, renal glomeruli, brush borders and peritubular fibrils of renal tubules, thymic medulla, brush borders of small intestinal mucosal cells, and cerebellar astrocytes, synaptic endings and synaptic glomeruli. In fibroblast monolayers, the antibody stained stress fibres in an interrupted pattern and in spreading fibroblasts, the antibody stained the microfibrillar network. Stress fibre staining was disrupted by treatment of cells with cytochalasin B. Immunoblots showed that the antibody reacted with a 200 K protein in 3T3 cells and with a preparation of myosin from rat liver.

Hybrids from normal, germ free, nude and neonatal mice produce monoclonal autoantibodies to eight different intracellular structures

The supernatants of hybrids produced by fusion of splenocytes from normal, germ free, nude and neonatal BALB/c mice with mouse NS-1 myeloma cells were examined for immunofluorescence reactivity with viable and acetone fixed monolayers of syngeneic mouse fibroblasts and mouse 3T3 cells and with viable cell suspensions of syngeneic mouse erythrocytes and thymocytes. The supernatants of 70 out of 419 (16.7%) hybrids from normal mice, 87 out of 627 (13.9%) from germ free mice, 28 out of 240 (11.7%) from nude mice and 42 out of 1020 (4%) from neonatal mice reacted with 8 different intracellular structures in mouse fibroblasts and 3T3 cells, and with rat and human fibroblasts. The reactive intracellular structures comprised stress fibres, intermediate filaments, cell membrane associated, golgi complex, cytoplasm, cytoplasmic vesicles, mitochondria and nuclei. Of 45 stable clones derived by limiting dilution, 43 produced IgM antibodies and two IgG2b antibodies. Only one out of the 2,306 (0.04%) hybrids produced an autoantibody to the surface membrane of mouse thymocytes. These results show that B cells with reactivity towards different intracellular structures are present in the normal B cell repertoire whereas surface reactive B cells may be deleted or more profoundly suppressed or anergic and unable to form viable Ig producing hybridomas.

Vimentin intermediate filaments in cultures of human meningiomas

Monolayer cultures of six human meningiomas and meningeal cells from a human foetus were examined by indirect immunofluorescence with a human autoantibody to intermediate filaments and with a monoclonal antibody to vimentin intermediate filaments. No difference could be demonstrated in the staining of an intricate fibrillar network in cultures of transitional, fibroblastic, psammomatous and sarcomatous meningiomas compared to those of human foetal meninges. Many meningotheliomatous meningioma cells showed staining of distinctive 'whorls' of intermediate filaments, an observation less frequently seen in fetal meningeal cells or in meningiomas of other histological types. Meningioma cells, pretreated with vinblastine, showed staining of rearranged filaments whose conformation and compactness varied from cell to cell. A striking observation frequently seen in transitional and psammomatous meningiomas was the staining of thick intermediate filament 'bands' bridging two contiguous meningioma cells. Immunoblotting experiments confirmed the presence of vimentin intermediate filaments in the cultured meningioma cells.

Vimentin organizing centre in cultured epithelial cells

Perinuclear buttons were identified in cultured epithelial cell lines, with monoclonal antibodies to vimentin, following treatment with drugs which disrupt intermediate filaments. These buttons appeared after 10 min when cells were exposed to 10 micrograms/ml vinblastine or cyclohexamide. After the drug was removed vimentin-containing filaments radiated from this button through the cytoplasm. In some cells peripheral buttons appeared, up to six in one cell. Within 1 h the filaments had reformed to a normal pattern for intermediate filaments. These buttons did not form in mesenchymal cell lines, mouse; rat and 3T3 fibroblasts. They appeared only in epithelial cell lines. Monoclonal antibodies to keratin and tubulin did not stain these buttons. These appear to be discrete entities separate from the microtubule organizing centre and to be found only in cultured epithelial cell lines. This structure may act as the organization centre for vimentin in cultured epithelial cell lines.

A monoclonal IgM smooth muscle antibody reactive with fibroblast stress fibres produced by immunization with Treponema pallidum

A monoclonal IgM smooth muscle antibody secreted by a hybrid (MMI-1) of mouse plasmacytoma NS-1 with spleen cells from mouse immunized with Treponema pallidum was detected by indirect immunofluorescence tests on frozen tissue sections and on acetone fixed monolayers of rat and human fibroblasts. The antibody did not react with acetone fixed smears of T. pallidum but reacted with smooth muscle fibres and with striations of skeletal and cardiac muscle. In non-muscle cells, the antibody stained liver in a 'polygonal' pattern, thymus with accentuated staining of the thymic medulla, renal glomeruli and the brush border and peritubular fibrils of renal tubules. In fibroblast monolayers, the antibody stained stress fibres in an interrupted pattern. Immunoblotting with muscle proteins and the antibody showed labelling of a 100K molecule. The cellular distribution of the mouse monoclonal antibody is similar to that obtained with anti-actin antibody suggesting that the corresponding antigen may be an actin binding protein.